Acrylonitrile polymers plasticized with phenolic esters of alkyl sulphonic acids



United States Patent 01 3,535,251 Patented Get. 20, 1970 US. Cl. 260-308 3- Claims AESTRACT OF THE DISCLOSURE Acrylonitrile polymers in filament, fibre, 0r film form having improved mechanical properties and containing as a plasticiser (a) aryl ester of an alkyl sulphonic acid having 6 to 18 carbon atoms in the alkyl group;

(b) mixtures of lower alkyl phthalate esters and the above sulphonic acid esters; or

(0) mixtures of lower alkyl phthalate and polyester of adipic acid.

This invention relates to a process for the production of filaments, fibres and films from acrylonitrile polymers in which the mechanical properties of the filaments, fibres and films are improved by the addition of plasticisers.

Numerous compounds have already been proposed as being suitable for use as plasticisers for polyacrylonitrile. For example, cyanoalkyl-sulphonamides, dioxanones, phthalic acid esters, polynitrile compounds and phosphine compounds, have been described as plasticisers for polyacrylonitrile. Plasticisers of this kind are added in quantities of 1 to 50% by Weight, depending upon the purpose for which the polymer is to be used. They may act either as permanent or as temporary plasticisers. In the production of filaments, fibres and films, plasticisers can only be added in a specific concentration range which is governed both by the particular type of addition and by the substrate. 1f the plasticiser is added in too large a quantity, the mechanical and thermal properties are unfavourably influenced. If, on the other hand, it is added in too small a quantity, it will not produce the required improvement in the permanent properties, such as the permanent flex- T ural index and fiexural abrasion resistance etc. The optimal concentration for the particular circumstances can readily be determined by experiment.

A process for the production of filaments, fibres and films with improved mechanical properties from acrylonitrile polymers has now been found, in which 1 to 20% either of an alkylsulphonic acid aryl ester having 6 to 18 carbon atoms in the alkyl group or of a mixture of an alkyl phthalate having 1 to 4 carbon atoms in each of the alkyl groups, with an alkyl sulphonic acid ester or a polymeric adipic acid ester, is added to the acrylonitrile polymers, which are then further processed to form filaments, fibres and films.

An example of a suitable alkyl phthalate having 1 to 4 carbon atoms in the alkyl groups is dimethyl phthalate. Polymeric esters of adipic acid and aliphatic diols with 2 to 8 carbon atoms, preferably butane diol or hexane diol, may be used as the polymeric adipates. The molecular weights of the polymeric adipates are advantageously from 1000 to 3500. Preferred alkyl sulphonic acid aryl esters are those which have been prepared from a mixture of phenol and cresol.

The filaments, fibres and films produced by the process according to the invention from acrylonitrile polymers, are distinguished from polyacrylonitrile films or materials which do not contain the plasticisers in the concentration range specified, by the fact that they exhibit significantly improved permanent properties (flexural and abrasion resistance indices), whilst their other technological properties show little or no change. It was discovered, surprisingly so, that, for example, their tensile strength is not only retained but, in fact, shows some improvement in the case of films. There is little or no increase in breaking elongation. In the case of films, the high brittleness and tendency to split or crack of a polyacrylonitrile film without any additives, can often give the impression of an increase in breaking elongation. The softening range of the filaments, fibres and films is not affected by the addition of the plasticisers used according to the present invention. It is also remarkable that the films in particular, but also the filaments and fibres produced in accordance with the present invention, show a greatly reduced tendency to split and fibrillate.

In order to produce filaments, fibres or films from acrylonitrile polymers in the presence of the plasticiser, an ester of an alkyl sulphonic acid and phenols or cresols may be added to the solutions of polyacrylonitrile in solvents such as dimethyl formamide, dimethyl acetamide and dimethyl sulphone, used to produce the filaments, fibres or films, after which these solutions are further processed by known methods to form the films, filaments or fibres.

It is also possible to make the acrylonitrile polymer into a paste with the plasticisers, before dissolution.

In the context of the present invention, filaments, fibres or films of acrylonitrile polymers also include structures of the same kind consisting of copolymers of acrylonitrile with other polymerisable monomers or of mixtures of these copolymers or of polyacrylonitrile with other polymers, providing the amount of acrylonitrile component is at least 80% by weight.

EXAMPLE 1 16% by weight based on polymer of a sulphonic acid ester, were added to a polyacrylonitrile spinning solution in dimethyl formamide containing 25% by weight of a copolymer of 95% by weight of acrylonitrile and 5% by weight of methyl acrylate. The sulphonic acid ester was the product of an aliphatic C -acid and a mixture of equal parts of phenol and cresol. The solution was spun in the usual way by the dry spinning method, stretched and fixed. The completed fibres had an individual denier of 15 and a residual dimethyl formamide content of approximately 1.5% by weight. For comparison purposes, an identical solution was spun and further processed in the same way, in the absence of the sulphonic acid ester.

The properties of the fibres are set out in Table 1 below.

The permanent fiexural index (number of folds or bends before failure) was measured on a Zweigle permanent flexure testing machine. It was enlarged to include ten measuring points, and the bending edge adapted to the testing denier of 15 den. During each test, the filament was subjected to a load equivalent to 10% of the tenacity.

The remaining technological properties were tested in accordance with the appropriate DIN specifications. The softening range was determined by measuring the tensile strain under heat at a load of 1.0 p./tex and a temperature increase of 1 C. per minute.

TABLE 1 Fibre with Fibre withplasticiscr of out plasti- Mcchanieal properties Example 1 ciser Average permanent flexural index (double e, 900 3, 200 l. 23 1. 27 7t) 91 Relative loop tcnacityfln 85 92 Initial E-modulus, kp./n1p 211) 200 Elastic recovery elongation (3 mins. load 3 mins. recovery period 04 67 Softening temperature, C 95-100 94*98 EXAMPLE 2 16% by weight based on polymer, of a sulphonic acid ester were added to a polyacrylonitrile spinning solution in dimethyl formamide containing 25% by weight of a copolymer of 95% by weight acrylonitrile and 5% by weight of methyl acrylate. The sulphonic acid ester was the product of a mixture of aliphatic acids with an average of 11 carbon atoms, and a mixture of equal parts of phenol and cresol. The solution was spun in the usual way by the dry-spinning method, stretched and fixed. The completed fibres had an individual denier of 15 den. and a residual dimethyl formamide content of approximately 1.5% by weight. For comparison, an identical solution was spun and further processed in the same way in the absence of sulphonic acid ester.

The properties of the fibres are set out in Table 2 below.

The permanent fiexural index (number of folds before failure) was determined on a Zweigle permanent flexure testing machine which had been enlarged to include measuring points and the bending edge adapted to the testing denier of denier. During each test, the load exerted on the filaments amounted to 10% of the tenacity. The bending edge of the permanent flexure tester used for this example had been provided with a smaller radius of curvature than had been used in Example 1.

This modification was made in order to obtain shorter testing times. The other technological properties were measured in accordance with the corresponding DIN specifications.

TABLE 2 Fibre with Fibre withplusticiserof out plasti- EXAMPLE 3 8% by weight based on polymer, of a sulphonic acid ester were added to a polyacrylonitrile spinning solution in dimethyl formamide containing by weight of a copolymer of 95% by weight of acrylonitrile and 5% by weight of methyl acrylate. The sulphonic acid ester was the product of a mixture of aliphatic acids with an average of 11 carbon atoms, and a mixture of equal parts of phenol and cresol.

Films approximately p. thick were drawn on a casting drum. The films were stretched 1:3.5 over an edge heated at 150 C., washed with hot water and tempered for 10 minutes at 140 C. They were then 12 thick and had a residual dimethyl formamide content of approximately 1.5% by weight. For comparison, a film was similarly prepared in the absence of a sulphonic acid ester.

The properties set out in Table 3 were measured on these films: Permanent flexural index according to DIN 53374 at 10% of the tenacity: tenacity and breaking clongation according to DIN 53371.

EXAMPLE 4 2% by Weight of dimethyl phthalate and 2% by weight of a sulphonic acid ester, based on polymer, Were added to a polyacrylonitrile spinning solution in dimethyl formamide containing 25% by weight of a copolymer of by weight of acrylonitricle and 5% by weight of methyl acrylate.

The sulphonic acid ester was the product of an aliphatic C -acid and a mixture of equal parts of phenol and cresol. The solution was spun in the usual way by the dry spinning process, stretched and fixed. The completed fibres had an individual denier of 15 den. and a residual dimethyl formamide content of 1.5% by weight. For comparison, an identical solution was spun and further processed in the same way in the absence of dimethyl phthalate and sulphonic acid ester.

The properties of the fibres are set out in Table 4 below.

The permanent fiexural index (number of folds before failure) was determined on a Zweigle permanent flexure testing machine which had been enlarged to include 10 measuring points, and the bending edge adapted to the testing denier of 15 den. The load placed on the filaments during each test amounted to 10% of the tenacity.

The wire abrasion index was determined by Grunewalds method (Chemiefasern, 1963, p. 853 ct seq.) under a load of 1 g. The other technological properties were measured in accordance with the appropriate DIN specifications. The tensile strain under heat was measured at a load of 1.0 p./tex at a temperature increase of 1 C. per

minute in order to determine the softening range.

TABLE 4 Fibre with Fibre plasticiscr of without Mechanical properties Example 4 plasticiser Average permanent flcxure index (double bends) 32, 500 6, 200 Average wire abrasion index (double strokes) 10,300 3, 200 Tenacity, p./dcn 1. 00 1. 27 Breaking elongation, percent U6 U1 Rel. loop tenacity, percent 92 Initial E-modulus, kpJrnmfl. 204 2H0 Torsion modulus, kp./min. 147 Elastic recovery at 5% elongation, percent (3 mins. load and 3 mius. recovery period) 60 67 Softening temperature, C 96-100 04-98 EXAMPLE 5 8% by weight of dimethyl phthalate and 8% by weight of a sulphonic acid ester, based on polymer, were added to a polyacrylonitrile spinning solution in dimethyl formamide containing 25% by weight of a copolymer of 95 by weight of acrylonitrile and 5% by weight of methyl acrylate. The sulphonic acid ester was the product of a mixture of aliphatic acids with an average of 11 carbon atoms, and a mixture of equal parts of phenol and cresol. The solution was spun in the usual way by the dry spinning process, stretched and fixed. The finished fibres had an individual denier of 15 den. and a residual dimethyl formamide content of approximately 11.5% by weight.

For comparison, an identical solution was spun and further processed in the same way in the absence of dimethyl phthalate and sulphonic acid ester.

The properties of the fibres are set out in Table 5 below.

The permanent flexural index (number of fOlds before failure) was determined on a Zwciglc permanent llcxure testing machine which had been enlarged to include measuring points, and the bending edge adapted to the testing denier of den. The bending edges of this machine had been provided with a smaller radius of curvature than had been used in Example 1. The object of this 6 ther processed in the same way in the absence of the plasticiser mixture.

The properties of the fibres are set out in Table 7 below.

The permanent flexural index (number of folds before was to shorten the testing time. The load placed on the 5 lure) Was determined on a Zweigle permanent flexfilament during each test amounted to 10% of the tenure testing machine which had been enlarged to include iry, 10 measuring points, and the bending edge adapted to The other technological properties were measured in the testing denier of 15. The load placed on the filament accordance with the corresponding DIN specifications. 1O amounted t0 10% 0f the tenacity- The Wife abrasion TABLE 5 dex was determined by Grunewalds method (cf. Chemiefasern, 1963, pp. 853 et seq.) at a load of 1 g. The tensile 555332; 55? strain under heat was determined at a load of 1.0 p./teX Mechanical properties Example5 plasticiser and a temperature increase of 1 per minute in order to Permanent repeated fixure index (double 15 determine the softening range. The other technological n 3 32 p perties were tested in accordance with the correspond- Bm inlgeiangaiar;been; II 41 55 1I1gDINSPec1fiatwnS= & hilii ifi aili 5 ml1$$ &%35?$?fl. 76 67 TABLE 7 Fibre with Fibre EXAMPLE 6 plasticiser of Without A mixture of 4% by Weight of dimethyl phthalate and Example 7 plastmser 4% by weight of a sulphonic acid ester, based on poly- 21, 300 e, 200 mer, was added to a polyacrylonitrile spinning solution g g g Wire abrasion index (double 7 200 3 200 in dimethyl formamide containing by Weight of a 25 Tenaert 'fl liIQI I:"I: Q L copolymer of 95% by weight of acrylonitrile and 5% by 5 weight of methyl acrylate. Initial E-modulus, kpjmmi 152 250 The sulphonic acid ester was the product of a mixture Yf 5% ,elongtioll (3n oad3m1n iecoveiy peuod) 65 67 of aliphatic acids with an average of 11 carbon atoms, S0fte11i11g1a11ge, C 8H1 94-95 with a mixture of equal parts of phenol and cresol. Films approx. 30a thick were drawn on a casting drum. The What We claimis: films. were then stretched 1235 over and edge heated at A plasticized acrylonitrile Polymer comprising a 9 wafhed Wlth hot Water and tempfared for 10 mixture of an acrylonitrile polymer containing at least mlns; at 9 The film W thlck f had 80% by weight of polymerized acrylonitrile and up to a residual dimethyl formamlde content of approximately 30 20% by weight of methyl acrylate and 1 to 20% by Weight by Welghtor companson: a film was procluced of the acrylonitrile polymer of a plasticizer selected from P F y 111 the absence of the aforementloned the group consisting of phenolic, cresolic, and mixed Plasmnsephke flllxturephenolic and cresolic esters of alkyl sulphonic acids,

The Propemes set out 111 Table 6 were determmed 011 wherein the alkyl radical has from 6 to 18 carbon atoms. these films: 2. The plasticized acrylonitrile polymer of claim 1 Repeated fiexul'all Index acwrdmg to N 53374 at wherein the polymer is a copolymer comprising 80 to of the Preaklng load; breakmg elongatlon and 95% by weight of acrylonitrile and 20 to 5% by weight nacity according to DIN 5 3371: of methyl acrylate TABLE 6 3. The plasticized polymer of claim 2 wherein the co- Filmwith Film polymer comprises 95% by weight of acrylonitrile and p sti is r of without 5% by weight of methyl acrylate.

Examplefi plastlciser Permanent repeated flexure inde 6&0? 2,1303 References Cited $351313?ii igfirifiih-afltjjj 1313 1019 UNITED STATES PATENTS 2,404,717 7/1946 Houtz 26030.8 EXAMPLE 7 2,426,728 9/1947 DAlelio.

A mixture of 8% by weight of a polyadipate and 8% 2,474,350 6/ 1949 Eilefman 3 3 by weight of dimethyl phthalate, based on polymer, was 2,503,245 4/ 1950 COOVel et a1 0 3 added to a polyacrylonitrile spinning solution in dimethyl 2,555,062 5/1951 Small et 2603 formamide containing 25% by weight of a copolymer of 2,559,172 7/1951 Schneider 1 a1 03 95% by weight of acrylonitrile and 5% by weight of 2,689,362 9/ 1954 KIIOWleS 30-8 methyl acrylate. The polyadipate had an average mo- 3,053,789 9/1962 De W 26030.8 lecular weight of 2000 to 2500. It had been prepared 3,323,365 6/1967 Aubrey from 66 parts by weight of adipic acid, 32 parts by 2,613,195 10/1952 r ig 2 weight of hexane diol and 22 parts by weight of butane 2,474,350 6/ 1949 Eilermafl 1360-30-8 diol.

The solution was spun in the usual way by the dry MORRIS LIEBMAN Pnmary Exammel' spinning process, stretched and fixed. The completed fibres p IC Assistant Examiner had an individual denier of 15 and a residual dimethyl formamide content of approximately 1.5% by weight. For comparison, an identical solution was spun and fur- U.S. Cl. X.R. 26031.6, 31.8 

